The use of microwaves to thaw solid organs or tissue viably preserved in the frozen state is intriguing and promising but elusive. The objectives of these experiments are (1) to continue to measure the electrical properties of frozen tissue, (2) to calculate the heating potential distribution of solid organs and to develop equipment to apply microwaves evenly to these organs, and (3) to prove properly prepared frozen solid organs are viable in mammalians. These objectives are identical with those outlined in PHS NIH AM 17865 01, 02, 03 (1976-1979). Progress under this grant has included the design and development and use of equipment to measure the electrical properties of frozen tissue. Measurements in saline, ice, and cryoprotectants have been made (Appendix I) (AM 17865-02, AM 17865-03). This proposal should complete the measurements using minced and perfused kidney and other tissues with varying cryoprotectant concentrations. The second objective depends on the data accumulated with the first objective and will be speeded by the development and use of the microthermometer. This equipment will be tested with the canine, rat and rabbit kidney.